ERTH 2020 Lecture 1: Journey Through the Solar System Class Notes
23 May 2018
School
Department
Course
Professor
Journey Through the Solar System
ERTH 2020
Lecture 1: General Structure of the Solar System
Sun
- Centre of the solar system – SUN
- The sun is the source of all the material in our solar system
- From a planetary nebula
- SUN – G type star (medium sized) which is very common
- Hallay though it’s sola yle
- Energy – nuclear fusion – the core 15 million K energy
- Mass: 2 x 10^30 kg
- 1.39 million km in diameter
- Star Life Cycle
- Controlled by the mass of the proto-star that was formed from a nebula
- SUN: sunlight star, red giant, nebula and a white dwarf star
- The material that makes up all the planets is only 0.134% the mass of the Sun
- Why is this significant? The sun ejecting this material was not a cataclysmic event
– just a fairly minor
- Sun is 5 billion years old
- Rate of fusion and amount of He to age the star
Planets
- Condensation of a planetary disk
- Was’t asoed ito the su
- Soeties does’t tu ito plaets, soeties just aetio disks
- Donut shape
- When condensing, atoms and molecules in the disk start to stick together
- Build into balls until they become planetesimals
- Attract others by gravity, not chance
- If occurring at high speed, breaks apart the built up masses
- Collisions and combinations eat up all the material, creating 8 stable planets which
swept their orbits clear
What is a planet?
- A body that orbits the Sun
- Is massive enough for gravity to make it spherical
- Has cleaned its neighbourhood of smaller objects
Accetionary Disk Model is correct because…
- Evidence from planetary motion – ecliptic plane
- Orbit in the same motion
- Rotate in the same direction (except for Venus)
- Moons also orbit in the same motion
find more resources at oneclass.com
find more resources at oneclass.com
Sept 14, 2017
Lecture 2
Earth impacts
- Planetary bodies have bolide impacts and craters (obvious features)
- Bolide impact
- Small asteroids that disintegrated i eath’s atosphee
- Frequency of impacts have decreased after
- Every century to millennium 50-100 m (small crater)
- Every million years (1 km) – tsunami, devastation and climate change
- 100 million years 10 km – 100 million years (mass extinctions)
- 128 known impact craters
- small: 10 in the last 10 000 years
- medium: 30-60 in the last 60 My
- large: 30
- any impact even over 6 km would already have been discovered
- We have dynamic systems on earth – which is overprinting these events like erosion
(weathering and transport)
- Processes that are overprinting our timeline
Moon
- Lunar surface – a lot more craters
- No atmosphere, impacts are preserved – even smaller ones
- Impact density changed on the moon, same as earth, over time
- Simple model for impact crater formation
- Compression stage/end contact, excavation stage and end excavation stage may
produce secondary craters around the main impact
- Thrown out material called ejecta
- Overprinting of impacts
- Impact equilibrium
- When new craters will no longer be detective because of the # of impacts – too
old
▪ Smaller the impacts the harder they are to see
▪ The older the surface, the harder it will be to see new impact craters
- Other planetary bodies should be different
▪ The surfaces are not the same, different ejecta type (also secondary
impacts)
▪ Gravity is different – different secondary impact effects
Dynamic Processes
- Volcanoes also overprint
- Erosion
- Faulting or Folding
Relative age determinations and recognizing dynamic processes
Missions Costs
- Cassini 3.3 Billion $ over 20 years
find more resources at oneclass.com
find more resources at oneclass.com
Lecture 3
- Absolute ages based on impacts
- Lunar impact history
- Subject to a continuous flux of impacters
- Crater density – a geologic unit that allows us to date it (relatively)
- Mare and highlands have been resurfaced
▪ Younger 3.8 Ga
- Absolute ages determined from crater density
- Surface of Mars
- Southern highlands > 3.8 Gyr
- Northern lowlands = 3.0 Gyr
- Large volcanoes: 3-1 Gyr
- Olympus Mons caldera: 100-2oo Myr
- Veus’ sufae
- Only large impactors can penetrate the dense atmosphere of Venus
- Surfaces of Asteroids
- Heavily cratered and only a few show activity
- But we have lots of these (meteorites)
- Geological events
- Use a proxy
- Determine an age of a mineral which we characterize carefully so we know when
it grew relative to the processes (recorded by the rock sample)
- Magmatic events: short lived, minerals grow in a magma so they are effectively
the same age as the igneous rock
- Impact melting – the minerals will be the same age as the impact
▪ Problem with overprinting
- Radiometric ages
- Uranium has three naturally occurring
- Radioactive – decays
- Using stable lead, we can compare the radiogenic lead to the stable one
-
Readings
- October 1957 Soviet > Sputnik sent to space
- Beginning of the space age
- Kennedy decision to send men to the moon
- Principle goals of space exploration:
- Origin and evolution of the Solar System
- The origin and evolution of life
- The poesses that shape huakid’s teestial eioet
- Earth based telescopic observations are the first step to determining the fundamental
characteristics of planetary objects
- First exploratory missions are usually flybys, collect data over a few hours/days when
they zoom by
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lecture 1: general structure of the solar system. Centre of the solar system sun. The sun is the source of all the material in our solar system. Sun g type star (medium sized) which is very common. Energy nuclear fusion the core 15 million k energy. Controlled by the mass of the proto-star that was formed from a nebula. Sun: sunlight star, red giant, nebula and a white dwarf star. The material that makes up all the planets is only 0. 134% the mass of the sun. The sun ejecting this material was not a cataclysmic event. Rate of fusion and amount of he to age the star. So(cid:373)eti(cid:373)es does(cid:374)"t tu(cid:396)(cid:374) i(cid:374)to pla(cid:374)ets, so(cid:373)eti(cid:373)es just a(cid:272)(cid:272)(cid:396)etio(cid:374) disks. When condensing, atoms and molecules in the disk start to stick together. Build into balls until they become planetesimals. If occurring at high speed, breaks apart the built up masses.
